1. Field of the Invention
The present invention relates to methods and an apparatus for controlling the acoustic characteristics of concert halls, multipurpose halls and the like.
2. Prior Art
With multipurpose halls or the like, orginarily the acoustic characteristics of the space surrounding the stage and that of other areas, for example the space surrounding the audience seating area, differ considerably. In contrast, concert halls which have been specifically designed for performing classic music and the like, so-called one-room type halls, generally demonstrate uniform acoustic characteristics throughout.
Multipurpose halls frequently include structural features not found in concert halls, such as the proscenium arch through which the space surrounding the stage and the space surrounding the audience seating area communicate. Additionally, multipurpose halls often incorporate removable acoustical reflectors in the space surrounding the stage. Halls employing acoustical reflectors offer certain advantages from the standpoint of the performers in that, because the stage area is relatively small space compared with the audience seating area, the sound reflected towards the performers has improved acoustic characteristics. On the other hand, it is very difficult to maintain uniform acoustic characteristics throughout this kind of hall. Because the musicians' perception of the acoustic characteristics of their musical performance differs considerably from that of the audience, performing in this kind of hall so as to deliver a musical performance having the best possible acoustic characteristics in the audience seating area is exceedingly difficult.
From the standpoint of the audience, the acoustic characteristics of conventional multipurpose halls lend to a sense of separation between the stage area where the musical performance is taking place and the audience seating area, in other words, the sense of presence perceived by the audience is insufficient. Putting it differently, the structural characteristics of conventional multipurpose halls lead to loss of acoustical similarity between the stage area and the audience seating area.
As one means to improve the acoustical similarity between the stage area and the audience seating area in a multipurpose hall, a method has been proposed wherein the acoustic characteristics of the hall are controlled so that early reflected sound and reverberation time are each equalized throughout the sound field in a hall. The sound field formed by an actual hall, however, is not a theoretical, ideal sound field, and further, since reverberation characteristics are determined by early reflected sound and reverberated sound within an actual hall, their sounds are not independent of one another. Thus, controlling the architectural structure of a hal so as to vary one of the two parameters will result in changes in the other parameter, for which reason uniform acoustic characteristics cannot be practically achieved throughout the interior of this kind of hall.